Influenza Surveillance Report 2007-2008 Season/MMWR Week 13
The influenza (flu) activity level for Texas for the week ending March 29, 2008 was “regional.” During week 13, 86 (10.3%) specimens tested by NREVSS laboratories in Texas were positive for influenza. The percentage of visits due to influenza-like illness (ILI) as reported by SPSN providers in Texas was below baseline. Flu activity in Texas in week 13 continued to decrease in most regions. Reports from Health Service Regions Reports were received from all 11 Health Service Regions (HSRs) for week 13. HSR 11 reported the same level of flu activity as week 12. All other regions reported a decrease in flu activity compared to week 12. For a map of Health Service Regions, please visit the following website: http://www.dshs.state.tx.us/regions/state.shtm Laboratory Results During week 13, twelve hospital laboratories and public health agencies across Texas reported conducting a total of 831 influenza tests (antigen, culture, and PCR) to the National Respiratory and Enteric Virus Surveillance System (NREVSS) sponsored by the Centers for Disease Control and Prevention (CDC). Of the 775 antigen detection tests performed, 28 were positive for influenza A/not subtyped and 54 were positive for influenza B. These results were reported from Bell, Bexar, Collin, Dallas, Harris, Lubbock, Nueces, Tarrant, and Webb counties. Positive PCR results for influenza A/not subtyped and influenza B were reported from Tarrant County. A total of 42 reports of culture-confirmed influenza were received from Scott and White Hospital Laboratory, Texas Children’s Hospital Laboratory, NREVSS, and other sources for the following counties: Influenza A/H1 (none) Influenza A/H3 (none) Influenza A/not subtyped Bexar County (13) Harris County Influenza B Bell County Bexar County (20) Dallas County Harris County (5) McLennan County
Additional positive results from point-of-care rapid flu tests were reported by providers throughout the state (see Texas map). Antigenic Characterization CDC has reported antigenic characterization results from 35 influenza isolates [8 influenza A/H1, 24 influenza A/H3, and 3 influenza B viruses] received from the DSHS Laboratory since the beginning of the 2007-08 flu season. Influenza A/H1 [8] • Eight (100%) of the seven viruses were characterized as A/Solomon Islands/3/2006, the influenza A/H1 component of the 2007-08 influenza vaccine for the Northern Hemisphere. Influenza A/H3 [24] • Two (8%) of the 24 viruses were characterized as A/Wisconsin/67/2005-like, the influenza A/H3 component of the 2007-08 influenza vaccine for the Northern Hemisphere.
Twenty-one (88%) of the 24 viruses were characterized as A/Brisbane/10/2007-like. A/Brisbane/10/2007 is a recent antigenic variant which evolved from A/Wisconsin/67/2005-like. • One (4%) of the 24 viruses showed somewhat reduced titers with antisera produced against A/Wisconsin/67/2005 and A/Brisbane/10/2007. Influenza B (B/Victoria/02/87 and B/Yamagata/16/88 lineages) [3] Victoria lineage [0] • The influenza B component for the 2007-08 influenza vaccine is a B/Malaysia/2506/2004-like virus, belonging to the B/Victoria lineage. Yamagata lineage [3] • Three (100%) of the three viruses were identified as belonging to the B/Yamagata lineage of viruses. These results are similar to national antigenic characterization results, which may be found in the CDC weekly flu report at http://www.cdc.gov/flu/weekly/. The DSHS Laboratory sends a representative sample of influenza viruses to the CDC throughout the flu season. Influenza-Associated Pediatric Mortality One influenza-associated pediatric fatality was reported during MMWR week 13, but the death occurred in MMWR week 6 (week ending February 9, 2008). The death occurred in a 3-year-old resident of Health Service Region 6/5S without significant underlying medical conditions. The child tested positive for influenza B by rapid flu test. In addition to influenza, the child had bacterial and viral coinfections. It is unknown whether the child received an influenza vaccination for the current season. As of week 13, Texas has reported seven influenza-associated pediatric deaths in the 2007-08 influenza season. School Closures and Institutional Outbreaks No school closures or institutional outbreaks were reported during week 13. Sentinel Provider Surveillance Network Seventy-five sentinel providers in Texas reported data to the U.S. Influenza Sentinel Provider Surveillance System (SPSN) on patients with influenza-like illness (ILI) and total patients seen for any reason during week 13. Of the 74 providers who reported seeing patients during week 13, 41 (55.4%) saw at least one patient with ILI. Of all patient visits during this week, 3.69% were due to ILI. The ILI baseline for the West South Central Region (Arkansas, Louisiana, Oklahoma, and Texas) of the United States is 4.3% for the 2007-2008 season. The baseline is the mean percentage of patient visits for ILI during non-influenza weeks for the previous three seasons plus two standard deviations.
PERCENTAGE OF VISITS FOR INFLUENZA-LIKE-ILLNESS REPORTED BY SENTINEL PROVIDERS IN TEXAS (4/7/2008 12:35:15 PM) Week 200740 200741 200742 200743 200744 200745 200746 200747 200748 200749 200750 200751 200752 # Reporting 84 88 86 85 95 87 79 91 84 84 80 68 77 Age 0-4 256 264 274 368 391 411 442 478 506 232 256 169 176 Age 5-24 163 255 270 290 276 314 306 317 298 290 265 197 201 Age 25-64 151 207 261 208 206 243 215 272 299 162 128 186 191 Age over 64 49 58 50 47 55 39 65 73 74 16 16 26 22 Total ILI 619 784 855 913 928 1007 1028 1140 1177 700 665 578 590 Total Patients 21410 25255 25776 26428 28213 25665 24713 22748 26193 20713 18711 15597 12436 % ILI 2.89 3.10 3.32 3.45 3.29 3.92 4.16 5.01 4.49 3.38 3.55 3.71 4.74
•
Week 200801 200802 200803 200804 200805 200806 200807 200808 200809 200810 200811 200812 200813
# Reporting 90 97 81 87 96 96 99 98 90 90 77 74 75
Age 0-4 217 373 289 369 601 557 528 423 421 343 255 125 142
Age 5-24 302 500 518 886 1208 1128 1035 787 575 466 363 148 213
Age 25-64 332 630 370 650 954 951 808 768 687 492 384 90 273
Age over 64 29 117 36 54 158 112 124 92 83 79 38 18 21
Total ILI 880 1620 1213 1959 2921 2748 2495 2070 1766 1380 1040 381 649
Total Patients 16520 25891 21940 23306 29106 29337 27815 26537 26598 24925 17742 12568 17600
% ILI 5.33 6.26 5.53 8.41 10.04 9.37 8.97 7.80 6.64 5.54 5.86 3.03 3.69
Percentage of Visits Due to Influenza-Like Illness (ILI), Texas Sentinel Provider Surveillance Network, 2007-2008
12.00%
10.00%
Percentage of Visits Due to ILI
8.00%
West South Central Region baseline
6.00%
4.00%
2.00%
0.00% 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 January 4 5 6 7 8 9 10 11 12 13
October
November
December
February
March
Reporting Week
Influenza-Like Illness (ILI) Data Texas Sentinel Provider Surveillance Network Flu Seasons 2003-2008
16.00% 14.00% Percentage of Visits Due to ILI 12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 October November December January February March April May
MMWR Reporting Week
2003-2004
2004-2005
2005-2006
2006-2007
2007-2008
National Influenza Activity Map The map showing influenza activity in the United States for MMWR week 13 is displayed below. The current U.S. flu weekly report may be found at: http://www.cdc.gov/flu/weekly/fluactivity.htm
For more information on flu surveillance activities in the State of Texas, please visit the following website: http://www.dshs.state.tx.us/idcu/disease/influenza/surveillance/
Statewide Influenza Activity For the Week Ending March 29, 2008 (MMWR Week 13)
County Influenza Activity Level*
No activity No report No information/ no reporters Flu A (confirmed by culture or PCR) Flu B (confirmed by culture or PCR) Flu A and B (confirmed by culture or PCR) Rapid test positive flu Influenza-like illness only (no laboratory confirmation)
State Activity Level as Reported to CDC
Widespread Regional Local Sporadic No activity
*Influenza activity level corresponds to current MMWR week only and does not reflect previous weeks’ activity.